As noted in earlier patents, notably Porat U.S. Pat. No. 6,099,658, it is increasingly important to clean a pool in the fastest time possible, while doing a thorough job. Efficiency is the most sought after goal in the industry. In the past, pool cleaning vehicles that could climb walls needed to proceed more slowly as they did so, to prevent becoming unstable, especially on the way down.
Porat, above, discloses a vehicle that continues its regular or primary speed on the way up a wall, but then on the return down, slows for a pre-determined period of time, until, hopefully, reaching the pool bottom, and then returning to the primary speed.
It was thought that on way down, in order not to destabilize the vehicle, the slower speed would be required. While, for typical known pool cleaning devices, this may or may not be effective, the net result is to slow down the cleaning of the pool. So ironically, the very thing that Porat is attempting to solve, namely, time efficient cleaning of the pool, is, at least, somewhat adversely affected by the proposed solution.
In Porat's defense, it must be said that the de-stabilization of the device would be more time costly than merely slowing down the device. For example, if the condition known as turtling occurs, namely where the vehicle is stuck upside down, on it's cover as illustrated in FIG. 2 (prior art), clearly this will take more time than merely slowing down the vehicle as it returns down a wall.
As described in FIG. 2, there is shown a pool cleaning device 10 climbing a pool wall 20. As the device 10 breaks the surface of the water 30, air enters the device. As is well known in the art, pool cleaning devices require a near neutral buoyancy in order to effectively go about cleaning the pool. Air entering the device 10 housing 40 can easily de-stabilize the required buoyancy causing the device 10 to fall from the wall, “head over heels” or to turtle. Once the device 10 turtles, it must manually be turned over and re-started.
As noted above, the Porat patent discloses a two speed motor to slow down the device 10 on its return down the wall. The housing of Porat is provided with an air opening which, it is hoped will evacuate enough air once the vehicle begins its return down the wall to prevent destabilization. The combination of the opening, plus the slow speed, are thought by Porat to accomplish its purpose of preventing de-stabilization and thereby more effectively cleaning the pool.
It is also worthy of note that the motor of Porat must be two speed in order to accomplish its disclosed purpose.
As noted above, slowing down the vehicle is in direct contrast to the stated need of cleaning the pool surface as quickly and as effectively as possible. What is needed is a pool cleaning vehicle that includes both structure and logic that minimize the possibility of de-stabilization as well as thoroughly clean the pool surfaces as quickly as possible.